is a Japanese documentary film directed by Masao Adachi about serial killer Norio Nagayama. Completed in 1969, it was first shown publicly in 1975. Adachi collaborated on the film with critic Matsuda Masao, directors Kà Âji Wakamatsu and Nagisa à Âshima, and screenwriter Mamoru Sasaki.
The soundtrack consists of free improvisations by Mototeru Takagi and Masahiko Togashi. An edited version of the soundtrack was released as Isolation by Columbia Records.